The present invention relates to a hydraulic door closing device.
In most offices and private homes, the doors in general and the entrance doors in particular are provided with an automatic door closing device fastened to the door frame and the door. Such a hydraulic device facilitates the slow and automatic closing of the door.
The conventional hydraulic door closing device is composed of a spring having a fixed tension, which must be overcome to cause the door to open. The spring of the conventional hydraulic door is generally devoid of a means capable of adjusting the tension of the spring at such time when the wind is gusty or when the weather is marked with a wild fluctuation of temperature. The climatic factors do play a role in affecting the viscosity of the oil in the automatic door closing device.
A hydraulic door closing device of the prior art is provided with a means capable of adjusting the tension of the spring of the hydraulic door closing device. Such an adjusting means comprises a threaded rod provided at the front end thereof with a guide member which is capable of urging one end of the spring and is capable of sliding in conjunction with the rotation of the guide member. The adjusting means further comprises an adjusting member, which is coupled with the rear end of the threaded rod for controlling the rotation of the guide member. The adjustment of the hydraulic door closing device is initiated by a hexagonal wrench, which is used to actuate the rotation of the threaded rod so as to trigger a forward movement or a backward movement of the guide member. As soon as the guide member has moved close to the rear end of the threaded rod, the spring is caused to compress. On the other hand, when the guide member has moved close to the front end of the threaded rod, the spring is caused to expand. When the spring is in a state of compression, a greater force is needed to open the door. On the contrary, when the spring is in a state of relaxation, the door can be opened with a little effort. However, the prior art hydraulic door closing device described above is by no means free from defects, which are expounded hereinafter.
The extent of the tension of the spring of the prior art hydraulic door closing device is adjusted by rotating the threaded rod of the adjusting means. In other words, the degree of the tension of the spring depends on the number of rotation that the threaded rod has been caused to turn. It often happens that a person, who is adjusting the tension of the spring, might easily mix up the rotation counts. In addition, the threaded rod is caused to rotate by a hexagonal wrench. As there is often a limited maneuvering space available between the hydraulic door closing device and the frame of the door to which the hydraulic door closing device is attached, the operation of rotating the threaded rod by a hexagonal wrench is often hampered.
The guide member of the adjusting means of the prior art hydraulic door closing device is often unable to move with precision in the direction of the axis of the threaded rod when the threaded rod rotates. Moreover, it happens at times that the guide member rotates without sliding forward or backward when the threaded rod rotates.